I. Field of the Invention
This invention relates to an improved assembly for developing kinetic energy in a rotary impact tool. Specifically, there is disclosed herein a two-part, readily assembled and disassembled pin cage-coupler which, until now, is mechanized as a unitary device. This two-piece realization lends itself not only to more economical fabrication and repair, but to more cost-effective production as well.
II. Discussion of the Relevant Art
There are presently rotary impact tools of great variety. One such tool employing a cage hammer uses two roller elements to transmit, impulsively, kinetic energy of the motor driven cage hammer to the anvil. This concept is disclosed in U.S. Pat. No. 3,174,597 and in a later diverse application, in U.S. Pat. No. 4,347,902, both of which deal with rotary tool clutch mechanisms. Current art utilizes a unitary cage hammer that contains the coupling means whereby angular force is taken off the motor output shaft. It is such current art that is improved by the instant invention in order to avoid limitations on production and repair that devolve from the unitary construction of cage hammer and coupling means. Further, the cost of production inherent in the unitary construction (further delineated hereinafter) has clearly militated the invention.
Separate production, or functional separation, of a coupler from a cage or inertial mass is not unknown in the art. In U.S. Pat. No. 2,463,656, there is disclosed a diametrically lobed disc, containing a centrally disposed spline receiver, and which is employed to fittingly engage knotches at one end of a bifurcated cylinder that serves as a hammer for a rotary impact tool. Because of designed movement between the halves of the split cylinder, the disc does not effectively plug the cylinder end and is only fitted loosely therein. Correspondingly, the cylindrical hammer effects an elliptically shaped inner surface that is completely unrelieved and not adapted for receiving rollers of the previously described and instant implements. Thus, neither the '656 hammer nor disc (coupling means) would prove suitable for use in the instant invention. Similar in appearance to this invention is the disclosure of U.S. Pat. No. 4,585,078 wherein a circular coupling disc is mated to an end of a cylindrically shaped hammer by means, of eccentrically disposed disc projections, that protrude in an axial direction, for engagement with chordwise disposed grooves at one end of the cylindrical hammer. The disc element of '078, called an intermediate member, rotates about a common axis of the tool while the eccentric projections, loosely engaging the chordwise grooves, cause the hammer member to rotatingly translate in a plane perpendicular to the axis of rotation. Such translational action is inconsistent with, and to be avoided by, those who would practice the instant invention.
Absent in the relevant art is any mention of deleterious effects of a radial translation by pins or rollers on the symmetry of a toroidal or annular cage. It has been observed that a deformation, oblate misshaping, may occur under certain operating conditions. To ameliorate this defect, a second embodiment, an adjunct mechanism is provided to the invention.
III. Incorporation by Reference
Patents disclosing elements of the present invention or rotary impact wrench clutch mechanisms, as improved hereby, namely, U.S. Pat. No.'s 2,463,656, 3,174,597, 4,347,902, and 4,585,078 are hereinafter incorporated by reference.